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The reconstruction of soft tissue defects after burn injuries or breast resection due to cancer are still an unresolved problem in plastic and reconstructive surgery. Since there are limited surgical possibilities, adipose tissue engineering with preadipocytes offers new perspectives. Essential requirements for successful reconstruction are: adequate threedimensional construct, autologous cells, ideal cultivation conditions and sufficient vascularization for further in vivo experiments. This study evaluates an innovative material consisting of polyesteramide in a 3D nonwoven seeded with preadipocytes, adipogenic precursor cells. Surface contaminations were removed by a surface cleaning procedure followed by vacuum drying and gamma sterilisation. Preadipocytes were isolated out of human subcutaneous adipose tissue of healthy patients who had undergone elective operations. After the isolation procedure, preadipocytes were cultivated in culture dishes and then seeded on the scaffolds. Nonwovens were either precoated with fibronectin or directly used for seeding. Scaffolds were then examined for preadipocytes proliferation and differentiation. To analyze the attitude of preadipocytes in vitro and later in vivo, preadipocytes were tracked with three different fluorescent dyes: PKH-26, CM-DiI and CFDA-SE. After the isolation procedure, preadipocytes were cultivated in culture dishes and stained with the cell tracker according to the recommendation of the manufacturer. Preadipocytes were cultivated for 30 days for microscopical and FACS analyses. The adipogenic conversion consists of several stages of development. As described in the literature, nitric oxide has an adipogenic effect on preadipocytes but shows inadequate differentiation. In order to evaluate this effect and optimize the concept of preadipocyte differentiation, different concentrations of the NO-Donor DETA/NO compared to DETA were used and the effect on preadipocytes was evaluated. After optimizing the cleaning procedures of the construct, the analyses of the nonwovens demonstrate good adherence and spreading of preadipocytes on polyesteramide derived nonwovens. Cells are adequately distributed and most cells are attached to fibers. Precoating with fibronectin displays a significantly higher cell number after seeding. Comparing the three tracking dyes, PKH-26 seems to be the most promising reagent considering toxicity and long-lasting of the labelling. All the three dyes had no effect on proliferation and differentiation of preadipocytes. Analyses with the NO-Donor DETA/NO approve the adipogenic effect of nitric oxide on preadipocytes, but with a low therapeutic index. The results of this study display that polyesteramides are promising materials with high potential for clinical application especially due their pH stability during degradation what leads to less formation of acid degradation products which are often responsible for inflammatory reactions after scaffold implantation. The fluorescent dyes used for optimizing the in vivo analyses are not applicable for long lasting experiments as the luminosity diminishes dramatically due to the high proliferation capacity of preadipocytes. The fact is that the major problem of tissue engineering is still unresolved: the insufficient vascularization. There are many approaches to solve this problem but further experiments are still necessary.

The present thesis deals with the synthesis and the properties of alternating poly(ester amide)s based on a,w-amino alcohols and cyclic anhydrides. The synthesis of the poly(ester amide)s is performed by polycondensation of linear AB-monomers (a-carboxyl-w-hydroxy amides), in some cases additionally by ring-opening polymerization of cyclic ester amides. The correlation between the structure of the poly(ester amide)s and their properties is discussed. Furthermore, mechanistic and kinetic aspects of the ring-opening polymerization of cyclic ester amides are investigated. The synthesis of AB- and ABA-block copolymers using poly(ethylene oxide) macroinitiators is described.

Novel polyesteramides were synthesized by copolymerization in bulk of 5-(4,5-dihydro-1,3-oxazol-2-yl)-1-pentanol and various cyclic dicarboxylic acid anhydrides at temperatures varying between 120 and 200°C. The polymers resulting from polycondensation were characterized by means of 1H–NMR, FTIR, MALDI–TOF–MS, SEC, and DSC. The glass transition temperatures, Tg, of the copolymers were varied between −28 and +31°C as a function of the anhydride type. Molecular weights, Mw, were dependent on reaction temperature, reaction time, and anhydride type. Spectroscopic investigation of reaction products and esteramide model compounds provided evidence for imide by-product formation, which accounts for the low degree of polymerization. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3367–3376, 1999

Polyesteramide 6NT6–polytetramethylene ether glycol (PTMEG) copolymers, precipitated from dilute solution, have been studied by small-angle x-ray scattering (SAXS) and wide-angle x-ray scattering (WAXS) with variation of the PTMEG content. A comparison of the structural characteristics of these materials has been made with those of the 6NT6 homopolymer. Chain folding is assumed as the crystallization mechanism for the low-PTMEG-content copolymers, with possible inclusion of polyether segments within the 6NT6 crystal lattice. WAXS data support the view of a weakening of the 6NT6 crystalline packing in the equatorial planes as the reason for broadening of the diffraction peaks, for changes in their relative intensities, and for the increase in the equatorial interplanar distances in the high-PTMEG-content samples. The annealing behavior has also been investigated.